tree-optimization/97255 - missing vector bool pattern of SRAed bool

tree-optimization/97255 - missing vector bool pattern of SRAed bool

SRA tends to use VIEW_CONVERT_EXPR when replacing bool fields with
unsigned char fields.  Those are not handled in vector bool pattern
detection causing vector true values to leak.  The following fixes
this by turning those into b ? 1 : 0 as well.

2020-10-01  Richard Biener  <rguenther@suse.de>

	* tree-vect-patterns.c (vect_recog_bool_pattern): Also handle
	VIEW_CONVERT_EXPR.

	* g++.dg/vect/pr97255.cc: New testcase.